Deeply nested code is often hard to understand and may be a sign that it needs to be refactored.
There are several good books on how to refactor code.
I like Martin Fowler's "Refactoring: Improving The Design of Existing Code".

The maximum number of nested control structures can be configured via a value for max_nests in a .perlcriticrc file.
Each for-loop,
if-else,
while,
and until block is counted as one nest.
Postfix forms of these constructs are not counted.
The default maximum is 5.
Customization in a .perlcriticrc file looks like this: